Parse Nested JSON Fields | Dataford Interview Questions

Write a function to parse a complex JSON object and extract specific nested fields.

Implement extract_fields(data, paths), where data is a JSON-compatible dictionary or list and paths contains dot-separated paths. Return a dictionary containing each requested path that exists. Dictionary components use key names, while list components use zero-based integer indexes. Omit paths that are missing or invalid.

Example: extract_fields({"user": {"id": 7}}, ["user.id"]) returns { "user.id": 7 }.

Constraints

data contains only JSON-compatible values: dictionaries, lists, strings, numbers, booleans, or null
1 <= len(paths) <= 100
Each path is non-empty and has at most 20 components
List path components are non-negative decimal indexes
Return paths that resolve successfully and omit missing or invalid paths

Function Signature

def extract_fields(data, paths):

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Problem

Write a function to parse a complex JSON object and extract specific nested fields.

Example: extract_fields({"user": {"id": 7}}, ["user.id"]) returns { "user.id": 7 }.

Constraints

data contains only JSON-compatible values: dictionaries, lists, strings, numbers, booleans, or null
1 <= len(paths) <= 100
Each path is non-empty and has at most 20 components
List path components are non-negative decimal indexes
Return paths that resolve successfully and omit missing or invalid paths

Function Signature

def extract_fields(data, paths):

Your question is Parse Nested JSON Fields. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.